1. Field of the Invention.
A switching mechanism which selectively shorts (or opens) an electrical circuit, in general, and, more particularly, a spring-powered switching mechanism which is capable of one-shot operation under specified conditions over a long period of time.
2. Prior Art.
There are many switching mechanisms for electrical circuits which are well known in the prior art. Many of these switching mechanisms are electromechanical in nature, such as relays or the like. Also, many of these electromechanical switching mechanisms are "one-shot" devices such as latching relays or the like. That is, upon the application of a control signal, the "one-shot" switching mechanism is triggered into a prescribed position or condition. Typically, in the case of latching relays or the like, the position or condition of the device is altered (to the original condition) by the application of a different (or further) control signal.
In addition, there are other well known switching mechanisms for electrical circuits which are known in the art. For instance, many of these switching devices are of the semiconductor type. Likewise, there are other types of switching mechanisms which are capable of operating only on relatively small voltage, current and/or power signals. Consequently, these switching mechanisms have somewhat limited capabilities and applications.
Also, there are situations wherein a remote or hostile environment is involved. In this case, the switching mechanism must be capable of reliable operation over a long period of time, for example years, in the remote or hostile environment. In this type of arrangement, the switching mechanism which is disposed in the remote or hostile environment must be adapted for utilization in a particular application on a high reliability basis.
Examples of such hostile or remote environments are in outer space, underwater, and underground applications combined with extremes of temperatures and pressures or the like. In these cases, it is frequently required to use electrical circuits which are provided in substantial numbers and/or substantial redundancy. In this case, it is possible to use switching mechanisms to control the operation of the circuit by selectively shorting (or disconnecting) certain redundant circuitry in order to reduce power consumption, delete defective circuitry, replace defective circuitry with operable circuitry, or merely alter the configuration of the circuitry.
One such application is the circuitry used in devices which convert solar energy to electrical energy in space vehicles. In this case, a plurality of solar energy storage or conversion circuits and/or devices are connected in appropriate series and parallel circuit arrangements.
It is possible to detect and determine whether or not each individual electrical or solar energy storage or conversion circuit is operating properly. This can be accomplished through remote telemetry or the like. Upon an indication that one or more of the solar energy storage or conversion circuits (or cells) is defective, it is highly desirable to excise the defective cell from the overall circuit or panel in order to prevent unnecessary shorting, loading or the like.
A simple but effective method of effecting this excising of the defective cells is to provide suitable short or shunt circuits which selectively bypass these cells or merely disconnect the cells from the remainder of the cells.
Thus, it is highly desirable to have a switching mechanism which can effect this switch operation on a high reliability basis after a potentially long time period.
For example, a space vehicle or satellite may be in orbit for a number of years before a solar cell or panel becomes defective. Then, and only then, is it desirable (or necessary) to remove the defective unit from the circuit. Consequently, the switching mechanism must then operate reliably.
Moreover, it is also as important that the switching mechanism, after operation to effect the shorting (or disconnection) of the circuit, is capable of remaining in the new position indefinitely. Otherwise, if the switching mechanism should revert to the original condition, the defective unit comes back into play, thereby causing improper operation.